P621Vascular contractility increases from newborn to senescence

Abstract

Introduction

Previous studies have shown that there are changes in the vascular smooth muscle contractility as a function of age. Because KCl elicits vasomotor contractility without receptor mechanism and via increasing intracellular Ca2+ it could serve as anindicator of contractile capacity of smooth muscle.

Hypothesis

We hypothesized that aging alters the magnitude of the contractile ability of isolated carotid arteries of rats.

We observed 3 phases of KCl-induced contractions as a function of age: phase 1) increased from newborn until the age of 2 month (8d: 1.9 ± 0.2mN, 2m: 4.7 ± 0.4mN), phase 2) there was no change in the magnitude of contraction from 1 month until adult age of 12 months (6m: 5.0 ± 0.1mN, 12m: 6.0 ± 0.3mN) and phase 3) it increased from 12 months until 30 months (24m: 10 ± 0.8mN, 30m: 11.8 ± 0.5mN, respectively). Mean arterial blood pressure increased until 6 months of age, than it decreased to 24 months of age.

Conclusions

These data show that the contractile ability of the smooth muscle increases with age, which may contribute to the increased peripheral vascular resistance and systemic blood pressure observed from newborn to senescent age.